System and method for cleaning a bioreactor

Abstract

A system, a kit, and a method of cleaning a bioreactor in which wastewater is treated, the bioreactor housing biomedia in suspension in the wastewater. The method includes withdrawing at least some of the wastewater from the bioreactor into a separator. The wastewater includes a mixture of sludge and water. The method further includes processing the withdrawn wastewater to separate at least some of the sludge from water. The method further includes returning at least some of the processed wastewater from the external housing to the bioreactor, the processed wastewater having a lower sludge content than the sludge content in the wastewater of the bioreactor before it was processed.

Description

SYSTEM AND METHOD FOR CLEANING A BIOREACTORFIELD OF TECHNOLOGY

[0001] The present technology relates to wastewater treatment, more specifically cleaning of a bioreactor used in a wastewater treatment process.BACKGROUND

[0002] In wastewater treatment, contaminants in wastewater, such as harmful bacteria, nitrogen, phosphorus, organic matter, and suspended solids are removed or reduced. Many different types of wastewater treatment exist to account for different types of wastewater and contaminants such as industrial, agricultural, municipal and agri-food.

[0003] Most wastewater treatments are based on biological treatments in which microorganisms are used to break down solids as well as the contaminants in the wastewater. The microorganisms convert dissolved and particulate organic matter, measured as biochemical oxygen demand (BOD), into cell mass. Wastewater treatments are performed in bioreactors such as dedicated tanks for example.

[0004] In biological wastewater processes known as attached bacterial growth or fixed-film wastewater treatments, media is provided in the bioreactor for the microorganisms to attach to and grow on to form a biofilm. As the biofilm thickens, some of it sloughs off the media and accumulates in the bioreactor as sludge. However, sludge accumulation can significantly reduce fluid pathways through the bioreactor and the media by which subsequent contaminants may contact the microorganisms, thereby leading to a slow down or stopping of the treatment of the wastewater. Sludge accumulation can also increase the oxygen demand and decrease the oxygen transfer efficiency. As such, cleaning of the bioreactor may eventually be required to maintain optimal performance.

[0005] Currently several methods are used to remove excess sludge from reactors, however these methods either fail to fully clean the reactor or are costly, time-consuming, and / or increase contamination risks. One approach involves shifting the biomedia within the bioreactor and extracting the sludge. However, this often results in partial sludge extraction and incomplete cleaning. Another technique is to1306174900.1remove the biomedia from the bioreactor. However, this is more expensive, labor-intensive, and increases risk of contamination and / or damage to the biomedia.

[0006] In view of the foregoing, there is a need for a system and a method of cleaning a bioreactor that addresses at least some of these drawbacks mentioned above.SUMMARY

[0007] It is an object of the present technology to ameliorate at least some of the inconveniences present in the prior art.

[0008] According to an aspect of the present technology, there is provided a method of cleaning a bioreactor in which wastewater is treated, the bioreactor housing biomedia in suspension in the wastewater, the method including: (i) withdrawing at least some of the wastewater from the bioreactor into a separator, the wastewater including a mixture of sludge and water; (ii) processing the withdrawn wastewater in the separator to remove at least some of the sludge; (iii) returning at least some of the processed wastewater from the separator to the bioreactor, the returned processed wastewater having less sludge content than a sludge content in the withdrawn wastewater; and (iv) repeating steps (i) to (iii) at least one more time.

[0009] In some embodiments, the separator comprises a centrifuge, and the processing of the withdrawn wastewater includes applying a centrifugal force to the withdrawn wastewater to separate the at least some of the sludge from the water.

[0010] In some embodiments, the centrifuge is housed in a truck.

[0011] In some embodiments, steps (i) to (iii) are repeated until the wastewater includes less than a predetermined concentration of suspended solids.

[0012] In some embodiments, the withdrawing the at least some of the wastewater from the bioreactor, and the returning the at least some of the processed wastewater to the bioreactor is performed via a pipe which is fluidly connected to the separator.2306174900.1

[0013] In some embodiments, the pipe includes a beveled tip, and the withdrawing the at least some of the wastewater from the bioreactor, and the returning the at least some of the processed wastewater to the bioreactor includes submerging the beveled tip of the pipe in the wastewater. In certain embodiments, the beveled tip is positioned close to a wall of the bioreactor, with an angled portion of the beveled tip substantially parallel to the wall. This can enable withdrawal of the wastewater whilst avoiding the biomedia in the bioreactor.

[0014] In some embodiments, the method further includes injecting a fluid into the wastewater before step (i). The fluid may be air.

[0015] In some embodiments, the injecting of the fluid includes injecting the fluid through the pipe.

[0016] In some embodiments, the method includes aspirating some of the wastewater from the bioreactor prior to step (i). The aspiration may comprise removing wastewater from near a wall of the bioreactor. The aspiration of some of the wastewater before step (i) may be performed before fluid is injected into the wastewater. In some embodiments, an amount of the wastewater aspirated may be sufficient to decrease a depth of the wastewater in the bioreactor by about 5 to about 15%.

[0017] In some embodiments, the method includes after step (iii), injecting clean water from an external source into the bioreactor. The clean water may comprise the removed wastewater after it has been processed to remove sludge therefrom.

[0018] In some other embodiments, the only liquid used to process the wastewater to remove sludge is the processed wastewater, and no water from an external source is used.

[0019] In some embodiments, the method is performed without removing the biomedia from the bioreactor.

[0020] In some embodiments, the withdrawing of the wastewater is performed without filtering or straining the wastewater.

[0021] According to an aspect of the present technology, there is provided a system for cleaning a bioreactor in which wastewater is treated, the bioreactor configured to house biomedia in suspension in the wastewater, the system including: a separator for processing the wastewater to separate at least some3306174900.1sludge from water in the wastewater, the wastewater including a mixture of sludge and the water; and a fluid conduit fluidly connecting the separator and the bioreactor through which at least some of the wastewater can be withdrawn from the bioreactor and through which processed wastewater from the separator can be injected back into the bioreactor.

[0022] In some embodiments, the separator comprises a centrifuge, which may be housed in a truck.

[0023] In some embodiments, the fluid conduit is a pipe.

[0024] In some embodiments, the fluid conduit has a beveled tip. An angle of the beveled tip may be any suitable angle for permitting the beveled tip to get as close as possible to a wall or floor of the bioreactor and to avoid contact with the biomedia. In some embodiments, the angle of the bevel tip is between about 30 degrees to about 60 degrees. In some embodiments, the bevel tip is about 45 degrees.

[0025] In some embodiments, the fluid conduit does not include a filter or a strainer.

[0026] In some embodiments, the system further includes a pump fluidly connected to the separator and the fluid conduit.

[0027] According to an aspect of the present technology, there is provided a kit for cleaning a bioreactor in which wastewater is treated, the bioreactor housing biomedia in suspension in the wastewater, the kit including: a separator for processing the wastewater to separate at least some sludge from water in the wastewater, the wastewater including a mixture of sludge and water; and a fluid conduit for fluidly connecting the separator and the bioreactor. The fluid conduit may be configured to withdraw at least some of the wastewater from the bioreactor and inject processed wastewater from the separator back into the bioreactor

[0028] In some embodiments, the separator comprises a centrifuge, which may be housed in a truck.

[0029] In some embodiments, the fluid conduit is a pipe having a beveled tip. The pipe may be configured to be removably attached to a hose of the separator or directly to the separator. In some embodiments, an adaptor may be provided for connecting the pipe to the hose or to the separator.

[0030] In some embodiments, the fluid conduit does not include a filter or a strainer.4306174900.1

[0031] In some embodiments, the kit further includes a pump fluidly connected to the separator and the fluid conduit.

[0032] According to certain embodiments of the present system, method and kit, a bioreactor can be cleaned by replacing fouled wastewater (which includes sludge accumulation) with water with a lower sludge content without needing to remove biomedia from the bioreactor. Unlike certain prior art systems, the present technology does not require the use of a filter or strainer to remove the wastewater whilst maintaining the biomedia within the bioreactor. With such prior art systems that rely on a filter or strainer, the filter and / or strainer can become clogged and require cleaning which further increases maintenance. Additionally, there is a head loss created due to the filter and / or strainer which causes an increase in energy consumption of the pumping equipment.

[0033] Providing a beveled tip on the fluid conduit can allow the beveled tip to be positioned close to walls, floors, comers or edges of the bioreactor where a density of biomedia is less than within the body of the wastewater, thus avoiding removal of the biomedia at the same time as the wastewater.

[0034] In embodiments of the present system, method and kit, the only fluid that is required to clean the biomedia is that of the wastewater itself after it has been processed to remove or reduce its sludge content. No additional liquid source, nor any associated equipment for pumping the additional liquid source, is required.

[0035] Embodiments of the present technology each have at least one of the above-mentioned objects and / or aspects, but do not necessarily have all of them. It should be understood that some aspects of the present technology that have resulted from attempting to attain the above-mentioned object may not satisfy this object and / or may satisfy other objects not specifically recited herein.

[0036] It must be noted that, as used in this specification and the appended claims, the singular form “a”, “an” and “the” include plural referents unless the context clearly dictates otherwise.

[0037] As used herein, the term “about” in the context of a given value or range refers to a value or range that is within 20%, preferably within 10%, and more preferably within 5% of the given value or range.5306174900.1

[0038] As used herein, the term “and / or” is to be taken as specific disclosure of each of the two specified features or components with or without the other. For example “A and / or B” is to be taken as specific disclosure of each of (i) A, (ii) B and (iii) A and B, just as if each is set out individually herein.

[0039] As used herein, the term “bioreactor” is to be taken to mean an apparatus or a place in which a biological reaction or process can be carried out to convert dissolved and / or suspended biological matter in wastewater, using microorganisms (e.g. bacteria). Bioeactors include tanks, wells, lagoons and ponds. The biological reaction includes, but is not limited to, nitrification, denitrification, phosphorus removal and / or carbon removal. The conversion may be aerobic, anaerobic or anoxic.

[0040] As used herein, the term “biomedia”, also known as a bacteria growth device or biofilm support media, is to be taken to mean any media or device having a surface suitable for bacterial growth and / or attachment.

[0041] As used herein, the term “water treatment system” is to be taken to mean a system for cleaning or purifying water such as domestic or industrial wastewater or highly polluted water or polluted water originating from any means.

[0042] As used herein, the term “body of water” is to be taken to mean any one or more volume(s) of water which is to be treated. The body of water may be a single body of water, or multiple bodies of water joined together. The body of water may be man-made or natural. The term “body of water” includes ponds, lagoons, basins, tanks, and combinations of the same.

[0043] Embodiments of the present technology each have at least one of the above-mentioned object and / or aspects, but do not necessarily have all of them. It should be understood that some aspects of the present technology that have resulted from attempting to attain the above-mentioned object may not satisfy this object and / or may satisfy other objects not specifically recited herein.

[0044] Additional and / or alternative features, aspects and advantages of embodiments of the present technology will become apparent from the following description, the accompanying drawings and the appended claims.BRIEF DESCRIPTION OF THE DRAWINGS6306174900.1

[0045] For a better understanding of the present technology, as well as other aspects and further features thereof, reference is made to the following description which is to be used in conjunction with the accompanying drawings, where:

[0046] Figure 1 is a schematic diagram of a bioreactor with a system for cleaning the bioreactor, according to an embodiment of the present technology;

[0047] Figure 2 is a schematic diagram of the system and the bioreactor of Figure 1; and

[0048] Figure 3 is a method of cleaning the bioreactor using the system of Figure 1.DETAILED DESCRIPTION

[0049] Although the embodiments of the present technology depicted herein comprise certain geometrical configurations and arrangements, not all of these components, geometries and / or arrangements are essential to the present technology and thus should not be taken in their restrictive sense, i.e. should not be taken as to limit the scope of the present technology. It is to be understood, as also apparent to a person skilled in the art, that other suitable components and co-operations thereinbetween, as well as other suitable geometrical configurations and arrangements may be used without departing from the scope of the present technology.

[0050] The present technology is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The present technology is capable of other embodiments and of being practiced or of being carried out in various ways. Also, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of "including", "comprising", or "having", "containing", "involving" and variations thereof herein, is meant to encompass the items listed thereafter as well as, optionally, additional items.

[0051] With reference to Figure 1, a bioreactor 10 for the treatment of wastewater in accordance with one embodiment of the present technology is depicted. The following description relates to treating wastewater in a bioreactor tank 12, referred to hereinafter as a tank 12. However, it is contemplated that the present technology can be equally used in or applied to any body of water or any combinations of7306174900.1bodies of water. The bioreactor 10 can be applied to treating wastewater discharged from residential, commercial, or community wastewater systems, as well as any liquids containing impurities in various fields including, but not limited to, industrial or agri-food wastewater. For this reason, expressions such as “wastewater” should not be taken to limit the scope of the present technology and should be taken to include all kinds of liquids or technical applications with which the present technology could be useful. The bioreactor may have any suitable shape or size. The bioreactor may have vertical or curved walls, the presently described system, method and kit being applicable to both configurations.

[0052] The bioreactor 10 is configured to house biomedia 14, sometimes referred to as a bacteria growth device or biofilm support media. In this embodiment, the biomedia 14 is suspended within the tank 12 of the bioreactor 10. However, it is contemplated that, in some embodiments, the biomedia 14 may be fixed. The biomedia 14 is configured so to offer a high surface area for which bacteria to attach, grow, and form biofilms, and may be made of any suitable material such as polymers, ceramics, or composites. The presently described system, method and kit is suitable for use with any configuration of biomedia, such as biomedia configured as intertwined ribbons as described in US 7,582,211, the contents of which are herein incorporated by reference in their entirety.

[0053] Overtime, as the biofilm thickens, sludge 16 (which refers herein to any solid content of the wastewater) may accumulate over time in the bioreactor 10 which may impact operation of the bioreactor 10. Thus, the bioreactor 10 may eventually need to be cleaned to remove the accumulated sludge 16.

[0054] With reference to Figures 1 and 2, a system 100 for cleaning the bioreactor 10 will now be described. The system 100 includes an external housing 102 which includes a separator 106 for processing the wastewater to remove at least some solid content, a fluid conduit 104 for fluidly connecting the separator 106 and the bioreactor 10, and a pump 108 for causing the wastewater to flow between the bioreactor 10 and the separator 106. The external housing 102 and the fluid conduit 104, or the separator and the fluid conduit 104, may be provided as a kit. The external housing 102 may be mobile permitting it to be moved from location to location.

[0055] The external housing 102 is configured to receive wastewater, which has a suspension of sludge and wastewater, from the bioreactor 10 via the fluid conduit 104. As mentioned above, the external housing 102 includes the separator 106 for processing the withdrawn wastewater. Specifically, the8306174900.1separator 106 is configured to separate the sludge from the withdrawn wastewater, such that the processed wastewater, which has a lower sludge content, can be returned back into the bioreactor 10. Thus, the total sludge content in the bioreactor is reduced. In certain embodiments, the external housing 102 is a centrifugal vacuum truck 102 and the separator 106 is a centrifuge 106 housed within the centrifugal vacuum truck 102, such as of the type used for cleaning septic tanks. The centrifuge 106 can selectively spin at high speeds, creating centrifugal force, which separates the sludge from the wastewater. The sludge may be retained in the centrifuge or associate storage tank, whilst the processed wastewater can be caused to flow back to the bioreactor 10. In some embodiments, the centrifugal vacuum truck 102 may include a filtration system to further facilitate the separation of sludge from the wastewater.

[0056] It is contemplated that the external housing 102 and the separator 106 may vary in other embodiments, for example the external housing 102 may comprise a tank or another type of housing. In other examples, the separator 106 may be a filtration system housed within the external housing 102. In further alternative embodiments, the external housing 102 may be a processing facility. It is further contemplated that the pump 108 may be configured differently in other embodiments, for example the pump 108 need not be housed in the external housing 102, as long as it is configured to cause wastewater to be withdrawn from the bioreactor 10 to the external housing 102. In yet further embodiments, the external housing 102 may be omitted.

[0057] The fluid conduit 104 is configured to fluidly connect the separator 106 and the bioreactor 10, thereby allowing wastewater to flow to the separator 106 for processing, and for the processed wastewater to flow back into the bioreactor 10. It is noted that, the fluid conduit 104 may comprise a single or a plurality of fluidly connected conduits. In this embodiment, the fluid conduit 104 comprises a pipe 110 connected to a hose 111 (Figure 2). The pipe 110, or at least a distal portion of the pipe 110, is configured to be disposed in the wastewater in the bioreactor 10. The hose 111 fluidly connects the pipe 110 to the separator 106, the hose 111 being disposed between the pipe 110 and the separator 106. The pipe 110 may be configured so that it can be removably connected to any type of hose 111. An adaptor (not shown) may be provided for enabling connection to the hose 111. The hose 111 may be removably connected to the separator 106. In other embodiments, the hose 111 may be omitted and the fluid conduit 104 may comprise only the pipe 110 fluidly connecting the separator 106 to the bioreactor 10. It is further contemplated that the configuration of the fluid conduit 104 may vary in other embodiments.9306174900.1

[0058] With specific reference to Figure 1, the distal portion of the pipe 110 comprises a tip 112 having an open end. A diameter of the pipe 110 at the tip 112 may be between about 1 to about 6 inches, for example 1 inch, 1.5 inch, 2 inch, 2.5 inch, 3 inch, 3.5 inch, 4 inch, 4.5 inch, 5 inch, 5.5 inch or 6 inch. The pipe 110 may be made of any suitable material such as a polymeric material.

[0059] According to aspects of the present technology, the tip 112 has a beveled configuration (i.e. angled). In some embodiments, the angle of the bevel tip is between about 30 degrees to about 60 degrees. In some embodiments, the bevel tip is about 45 degrees. The angled shape of the tip 112 may permit closer contact with a wall 18 or floor of the tank 12 where there may be less biomedia, thereby helping to avoid aspirating the biomedia while aspirating the wastewater. It is noted that, due to the beveled shape of the tip 112, the fluid conduit 104 does not require any filtering components, such as a strainer or a filter within or on any portion of the fluid conduit 104 to avoid suction of the biomedia. Therefore, a risk of clogging of the fluid conduit 104 is mitigated and the energy consumption of the pump 108 may be reduced.

[0060] After causing the wastewater to flow from the bioreactor 10 to the separator 106, separation of the sludge and wastewater occurs in the separator 106, and the now processed wastewater with a lower sludge content can be returned back to the bioreactor.

[0061] With reference to Figure 3, a method 200 of cleaning the bioreactor 10 using the system 100 will now be described. Broadly, the method 200 includes, at step 202, causing wastewater to flow from the bioreactor 10 into the centrifugal vacuum truck 102 and the separator 106; at step 204, causing the separator 106 to process the withdrawn wastewater to separate at least some of the sludge from the wastewater to generate processed wastewater with less sludge content; and, at step 206, causing at least some of the processed wastewater to flow back to the bioreactor 10 whilst the sludge remains outside of the bioreactor 10. The method 200 will now be described in greater detail. It is noted that the method 200 described below is exemplary and not limiting, as such certain steps within the method 200 may be omitted and / or re-ordered without departing from the scope of the present technology.

[0062] The method 200 optionally begins with withdrawing at least some of the wastewater from the bioreactor 10. The wastewater withdrawal can be performed by placing the beveled tip of the pipe 110 in the bioreactor and submerging the beveled tip in the wastewater, proximate a wall or floor of the10306174900.1bioreactor. The wastewater withdrawal can be performed at any depth of the wastewater, in some embodiments, the beveled tip is disposed in an upper portion of the wastewater, where there is generally less sludge than a lower portion. The amount of wastewater that is withdrawn may comprise a volume or a depth within a certain range. Advantageously, by initially aspirating a portion of the wastewater, a level of the wastewater in the bioreactor 10 is reduced, thereby avoiding or minimising overflow spillages from the bioreactor 10 during subsequent steps, which could potentially contaminate the surrounding environment. In some embodiments, the volume of wastewater removed is between about 4% and 15% of the total volume of wastewater within the bioreactor 10. In some embodiments, a depth of the wastewater that is lowered is between about 4% and 15% of the total depth of wastewater within the bioreactor 10. In some embodiments, wastewater removal lowers the wastewater depth by about 5-6 inches. However, it is noted that the volume and depth reduction may vary depending on the bioreactor 10 size and depth. It is contemplated that, in alternative embodiments, this step may be omitted depending on the depth and volume of the wastewater in the bioreactor 10. The wastewater that is removed from the bioreactor 10 may be further processed for sludge removal, or discarded.

[0063] The method 200 continues with a step of injecting a fluid into the wastewater contained within the bioreactor 10. Specifically, during this step, the fluid is air which is injected into the bioreactor 10 prior to withdrawing the wastewater (at step 202). The air injection provides agitation within the wastewater which may help with sludge dislodging and break-up. In this embodiment, the air is injected via the pipe 110 which is fluidly connected to the pump 108, or another pump, and an air source. However, it is contemplated that, in other embodiments, a separate fluid conduit may be used to inject the air into the bioreactor 10. It is further contemplated that, in other embodiments, a different fluid, such as fresh water, may be injected into the bioreactor 10 to agitate the wastewater.

[0064] The method continues, at step 202, with withdrawing the wastewater from the bioreactor 10. As discussed above, the wastewater which is withdrawn includes a mixture of sludge 16 and water. The beveled tip of the pipe 110 is placed in the wastewater, near a wall or a floor of the bioreactor, and the pump 108 of the centrifugal vacuum truck 102 is caused to apply a negative pressure, thereby causing the wastewater to flow from the bioreactor 10, through the tip 112 of the pipe 110 and the hose 111, into the centrifuge 106.11306174900.1

[0065] The method 200 continues, at step 204, with processing the withdrawn wastewater to separate sludge from the wastewater. As discussed above, in this embodiment, the withdrawn wastewater is processed using the centrifuge 106 of the centrifuge vacuum truck 102, thereby separating the sludge 16 from the wastewater. Specifically, the wastewater enters the centrifuge 106, where centrifugal force is applied. The centrifuge 106 spins the withdrawn wastewater at high speeds, causing the sludge to move outwards, separating from the wastewater. The sludge may be retained in a storage of the separator, or discarded.

[0066] Once the sludge 16 is separated from the wastewater, the now processed wastewater can be returned to the bioreactor 10. That is, the method 200 continues, at step 206, with returning at least some of the processed wastewater from the centrifuge vacuum truck 102 to the bioreactor 10. In this embodiment, the processed wastewater is delivered back into the bioreactor 10 via the fluid conduit 104 and the pipe 110 and the hose 111. However, it is contemplated that, in other embodiments, additional fluid conduit(s) may be used to return the processed wastewater. The processed wastewater is returned at a flow rate of about 300 gpm, however this flow rate may vary in other embodiments.

[0067] In certain embodiments, any one or more of the following advantages can be achieved through such recycling of the processed wastewater: a risk of introducing external contaminants to the bioreactor 10 is reduced; an overall water consumption is decreased by reducing an amount of additional fresh water that is required to fill the bioreactor 10; an environmental footprint is reduced by lowering an amount of wastewater that is discharged to the environment; and operating costs are reduced by cutting down on water supply expenses.

[0068] In certain embodiments, the method 200 continues with repeating steps 202 to 206. The repeated steps can be considered as a rinse using the aspirated wastewater from which the sludge has been removed. It is noted that the rinse improves the efficiency of the sludge removal from the bioreactor without requiring additional fluids (such as additional water or air) and / or additional equipment (such as a compressor for injecting additional air), thereby reducing costs, overall water consumption, and an environmental footprint. In some embodiments, steps 202 to 206 may be repeated three times or four times or five times and / or until a predetermined concentration of suspended solids (such as microbial biomass, organic debris, and / or inorganic debris) is reached within the tank 12 of the bioreactor 10. In12306174900.1certain embodiments, confirmation of the predetermined concentration of suspended solids is obtained visually. In other embodiments, the method 200 may include a step of obtaining a sample of wastewater from the bioreactor for gravimetric analysis. It is noted that, in alternative embodiments, steps 202 to 206 may only be performed once, thus omitting repetition of these steps.

[0069] After step 206 (whether steps 202 to 206 were repeated or not), the method 200 continues with an optional step of injecting clean water from an external water source into the bioreactor 10, thereby filling the bioreactor 10 to an appropriate volume or depth level. In some embodiments, the fluid conduit 104 is used to deliver the clean water. In other embodiments, a different fluid conduit and / or fluid delivery system may be used for injecting the clean water.

[0070] It is noted that the method 200 of the present embodiment is completed without the need of removing the biomedia 14 from the bioreactor 10. Thus, avoiding the need to dismantle and re-install the biomedia 14 in the bioreactor 10. This reduces the labor time and costs, preserves microbial communities on the biomedia 14, and mitigates risk of potential damage to the biomedia 14.

[0071] It should be appreciated that the scope of the technology is not limited to the particular embodiments described and illustrated herein but includes all modifications and variations falling within the scope of the invention as defined in the appended claims.13306174900.1

Claims

What is claimed is:

1. A method of cleaning a bioreactor in which wastewater is treated, the bioreactor housing biomedia in suspension in the wastewater, the method comprising:(i) withdrawing at least some of the wastewater from the bioreactor into a separator, the wastewater including a mixture of sludge and water;(ii) processing the withdrawn wastewater in the separator to remove at least some of the sludge;(iii) returning at least some of the processed wastewater from the separator to the bioreactor, the returned processed wastewater having less sludge content than a sludge content in the withdrawn wastewater; and(iv) repeating steps (i) to (iii) at least one more time.

2. The method of claim 1, wherein the separator comprises a centrifuge, and the processing of the withdrawn wastewater comprises applying a centrifugal force to the withdrawn wastewater to separate the at least some of the sludge from the water.

3. The method of claim 2, wherein the centrifuge is housed in a truck.

4. The method of claim 1, wherein steps (i) to (iii) are repeated until the wastewater includes less than a predetermined concentration of suspended solids.

5. The method of any one of claims 1 to 4, wherein: the withdrawing the at least some of the wastewater from the bioreactor, and the returning the at least some of the processed wastewater to the bioreactor is performed by a pipe which is fluidly connected to the separator.

6. The method of claim 5, wherein: the pipe comprises a beveled tip, and the withdrawing the at least some of the wastewater from the bioreactor, and the returning the at least some of the processed wastewater to the bioreactor comprises submerging the beveled tip of the pipe in the wastewater.

7. The method of any one of claims 1 to 6, further comprising injecting a fluid into the wastewater before step (i).

8. The method of claim 7, wherein the fluid is air.

9. The method of claim 7 or 8 when dependent on claim 4, wherein the injecting of the fluid comprises injecting the fluid through the pipe.

10. The method of any one of claims 1 to 9, further comprising withdrawing some of the wastewater from the bioreactor prior to step (i).

11. The method of any one of claims 1 to 10, further comprising, after step (iii), injecting clean water from an external source into the bioreactor.

12. The method of any one of claims 1 to 11, wherein the method is performed without removing the biomedia from the bioreactor.

13. The method of any one of claims 1 to 12, wherein the withdrawing of the wastewater is performed without filtering the wastewater.

14. A system for cleaning a bioreactor in which wastewater is treated, the bioreactor configured to house biomedia in suspension in the wastewater, the system comprising: a separator for processing the wastewater to separate at least some sludge from water in the wastewater, the wastewater including a mixture of sludge and water; and a fluid conduit fluidly connecting the separator and the bioreactor through which at least some of the wastewater can be withdrawn from the bioreactor and through which processed wastewater from the separator can be injected back into the bioreactor.

15. The system of claim 14, wherein the separator comprises a centrifuge.

16. The system of claim 14 or 15, wherein the fluid conduit is a pipe.

17. The system of any one of claims 14 to 16, wherein the fluid conduit has a beveled tip.

18. The system of any one of claims 14 to 17, wherein the fluid conduit does not include a filter or a strainer.

19. The system of any one of claims 14 to 18, further comprising a pump fluidly connected to the separator and the fluid conduit.

20. A kit for cleaning a bioreactor in which wastewater is treated, the bioreactor housing biomedia in suspension in the wastewater, the kit comprising: a separator for processing the wastewater to separate at least some sludge from water in the wastewater, the wastewater including a mixture of sludge and the water; and a fluid conduit for fluidly connecting the separator and the bioreactor.

21. The kit of claim 20, wherein the separator comprises a centrifuge.

22. The kit of claim 20 or 21, wherein the fluid conduit is a pipe.

23. The kit of any one of claims 20 to 22, wherein the fluid conduit has a beveled tip.

24. The kit of any one of claims 20 to 23, wherein the fluid conduit does not include a filter or a strainer.

25. The kit of any one of claims 20 to 24, further comprising a pump configured to fluidly connect to the separator and the fluid conduit.

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